1. Field of the Invention
The present invention relates to a core unit and a wire harness.
2. Description of the Related Art
Conventionally, in a vehicle, such as a hybrid vehicle or an electric vehicle, an inverter and a motor have been connected with each other via electric wires of three phases to supply power from the inverter to the motor. In such power supply from the inverter to the motor, there exists the case that a steeply risen voltage included in an output from the inverter causes an excessive surge voltage in a wire harness that connects the inverter and the motor, and the surge voltage is input to the motor.
As a method for suppressing such surge voltage, it is effective to wind an electric wire around a magnetic substance core. Here, when a plurality of electric wires are used, in terms of suppressing the increase in number of parts, it is preferable to wind the plurality of electric wires around one magnetic substance core. Japanese Patent Application Laid-open No. 2012-230851 discloses a technique of a wire harness having a primary coil formed by winding a plurality of AC lines around a ferrite core formed in a ring shape.
When the electric wires that are different in phase from each other and wound around the magnetic substance core are brought closer to each other, an electrostatic capacitance between the electric wires becomes large thus lowering cable impedance. There may be a case that the decrease of the cable impedance causes the increase of the surge voltage due to the inconsistency of the impedance in a whole circuit.